Optical see-through HMD calibration: a stereo method validated with a video see-through system

This paper presents initial results from an ongoing work to calibrate optical see-through head-mounted displays (HMDs). We have developed a method to calibrate stereoscopic optical see-through HMDs based on the 3D alignment of a target in the physical world with a virtual object in user’s view. This is an extension of the Single Point Active Alignment Method (SPAAM) [28] developed for monocular HMDs. Going from the monocular to the stereoscopic optical HMDs for calibration purposes is not straightforward. This is in part due to the perceptual complexity of stereo fusion process bringing up completely new challenges including the choice of the shape of the virtual object, the physical target and how to display the virtual object without any knowledge of the characteristics of the HMD and eye combination, i.e. the projection model. In this paper we have addressed these issues and proposed a solution for the calibration problem which we have validated through experiments on the seethrough HMD system described in [25]. By experimenting, we have found the appropriate type of virtual objects and physical features to be used in the 3D alignment. Furthermore, we have measured how good the alignment and calibration actually are.